New York: Olympic gymnastics superstar Simone Biles revealed on Monday she was sexually abused by disgraced former USA team doctor Larry Nassar, who was last month jailed for 60 years on child porn charges.

In a statement posted on Twitter, Biles said she had wrestled with her decision to go public with her story since the scandal broke.

"Most of you know me as a happy, giggly, and energetic girl," the 20-year-old reigning Olympic all-around champion wrote.

File photo of Larry Nassar. AP

"But lately I've felt a bit broken and the more I try to shut off the voice in my head, the louder it screams. I am not afraid to tell my story anymore. I too am one of the many survivors that was sexually abused by Larry Nassar," the 10-time World Championship medallist added.

Nassar has been accused of sexually assaulting more than 100 young girls including several US Olympians.

Biles's teammates Aly Raisman, McKayla Maroney and Gabby Douglas are among the members of USA Gymnastics squads who have said they were sexually assaulted by Nassar.

The 54-year-old was sentenced to 60 years in prison in December on child pornography charges.

He could be jailed for life when a further sentencing hearing gets under way in Michigan this week on separate sexual assault charges to which he has pleaded guilty.

In her statement on Twitter, Biles described her torment as she attempted to grapple with the abuse she had suffered.

"There are many reasons that I have been reluctant to share my story, but I now know it is not my fault," she wrote. "It is not normal to receive any type of treatment from a trusted team physician and refer to it horrifyingly as the 'special' treatment. This behavior is completely unacceptable, disgusting, and abusive, especially coming from someone whom I was TOLD to trust.

"For too long I've asked myself 'Was I too naive? Was it my fault?' I now know the answer to those questions. No. No, it was not my fault. No, I will not and should not carry the guilt that belongs to Larry Nassar, USA Gymnastics and others.

"It is impossibly difficult to relive these experiences and it breaks my heart even more to think that as I work towards my dream of competing in Tokyo 2020, I will to have to continually return to the same training facility where I was abused."

Biles, however, insisted it would not affect her passion for the sport.

"I love this sport too much and I have never been a quitter. I won't let one man and the others that enabled him, to steal my love and joy," she wrote, demanding an inquiry into how Nassar had been able to continue abusing for so many years.

"We need to know why this was able to take place for so long and to so many of us. We need to make sure something like this never happens again."

Biles's teammate Raisman swiftly took to Twitter in solidarity. "You are incredible Simone. I stand with you," Raisman wrote. "I know we will all get through this together."

USA Gymnastics issued a statement saying the organisation was "absolutely heartbroken, sorry and angry that Simone Biles or any of our athletes have been harmed by the horrific acts of Larry Nassar."

"USA Gymnastics will continue to listen to our athletes and our members in our efforts of creating a culture of empowerment with a relentless focus on athlete safety every single day," it added.

Nassar has been accused of molesting more than 100 female athletes during the three decades he worked with USA Gymnastics.

His case was part of a wide-ranging scandal which forced the resignation of USA Gymnastics chief Steve Penny in March last year.

Penny was accused by victims of failing to quickly notify authorities about abuse allegations.

USA Gymnastics adopted a new "safe sport policy" in response to the Nassar scandal that requires "mandatory reporting" of suspicions of sexual abuse.

A civil lawsuit has been filed on behalf of about 100 of Nassar's victims. Their attorney, John Manly, has said the total number could be as high as 160.